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Acceptability and usability of smartphone-basedBrainwave Entrainment (BWE) technology used byindividuals with chronic pain in a home settingDOI:10.1177/2049463720908798

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Citation for published version (APA):Locke, H., Brooks, J., Arendsen, L. J., Jacob, N. K., Casson, A., Jones, A., & Sivan, M. (2020). Acceptability andusability of smartphone-based Brainwave Entrainment (BWE) technology used by individuals with chronic pain in ahome setting. British journal of pain. https://doi.org/10.1177/2049463720908798

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1

Acceptability and usability of smartphone-based Brainwave Entrainment

(BWE) technology used by individuals with chronic pain in a home setting

Authors: Helen N Locke 1,2,*, Joanna Brooks 3, Laura J Arendsen 4, Nikhil Kurian

Jacob 5, Alex Casson 5, Anthony KP Jones 6 and Manoj Sivan 1,2,6

1 Academic Department of Rehabilitation Medicine, Leeds Institute of

Rheumatology and Musculoskeletal Medicine, University of Leeds, UK

2 Leeds Community Healthcare NHS Trust and Leeds Teaching Hospitals NHS

Trust, UK

3 Manchester Centre for Health Psychology, University of Manchester, UK

4 Division of Functional and Restorative Neurosurgery, Eberhard Karls University of

Tübingen, Germany

5 Department of Electrical and Electronics Engineering, University of Manchester,

UK

6 Human Pain Research Group, Division of Neuroscience and Experimental

Psychology, University of Manchester, UK

* Address for Correspondence: Dr Helen N Locke, Academic Department of

Rehabilitation Medicine, D Floor, Martin Wing, Leeds General Infirmary, Leeds

LS1 3EX, UK

E-mail: h.n.locke@leeds.ac.uk

Short title: Smartphone Brainwave Entrainment technology and chronic pain

2

ABSTRACT

Background:

Brainwave entrainment (BWE) using rhythmic visual or auditory stimulation has many

potential clinical applications, including in the management of chronic pain, where

there is a pressing need for novel, safe and effective treatments. The aim of this study

was to gain qualitative feedback on the acceptability and usability of a novel BWE

smartphone application, to ensure it meets the needs and wishes of end users.

Methods:

Fifteen participants with chronic pain used the application at home for four weeks.

Semi-structured telephone interviews were then carried out. A template analysis

approach was used to interpret the findings, with an initial coding template structured

around the constructs of a theoretical framework for assessing acceptability of

healthcare interventions. Structured data analysis generated a final modified coding

structure, capturing themes generated across participants’ accounts.

Results:

The four main themes were: ‘approach to trying out the app: affective attitude and

ethicality’; ‘perceived effectiveness’; ‘opportunity costs and burden’ and ‘intervention

coherence and self-efficacy’. All participants were willing to engage with the

technology and welcomed it as an alternative approach to medications. Participants

appreciated the simplicity of design and the ability to choose between visual or

auditory stimulation. All participants felt confident in using the application.

Conclusion:

The findings demonstrate preliminary support for the acceptability and usability of the

3

BWE application. This is the first qualitative study of BWE to systematically assess

these issues.

Keywords: Mobile applications; alpha rhythm; EEG phase synchronization; pain

perception; pain management

4

BACKGROUND

Pain is a physiological marker of illness or injury, and can be considered a learning

signal (1). However, when pain is chronic it is associated with a range of physical and

psychological pathologies (2,3). Chronic pain is a significant health problem affecting

around 20% of adults in Europe (4), and is one of the largest contributors to adult-

onset disability worldwide (5,6). The cost associated with chronic pain is estimated to

exceed that of cancer, diabetes or heart disease (7,8).

The mainstay of treatment for chronic pain is with pharmacological therapies such as

opioids and non-steroidal anti-inflammatory drugs (NSAIDs). Yet, evidence for the

effectiveness of long-term opioid treatment is limited and NSAIDS are not

recommended for long-term use. Moreover, both come with a risk of serious side

effects (9–13). Thus, there is a pressing need for effective, safe, and accessible

alternatives for the treatment of chronic pain.

A target of considerable interest for the development of novel treatment approaches

is the brain’s response to pain. Pain experience is the result of an integration of

sensory pain information and various other influences including attention, emotions,

and expectations within a widespread brain network called the pain matrix (14–16).

Chronic pain is associated with changes in brain structure and function (17–19) and

increased activity in brain regions involved in emotional processing of pain (20).

Therefore, brain-stimulation techniques that can modulate these responses (“neuro-

therapies”) could be used to relieve pain (21).

5

A particularly promising target for neuro-therapies is alpha activity - oscillatory brain

activity at 8-12Hz that can be measured using electroencephalography (EEG). Alpha

activity has an active role in coordinating the processing of incoming sensory

information, including sensory pain information. Moreover, frontal alpha in particular

has been linked to functions of top-down control (22), attention (22,23) and the

modulation of pain perception by placebo-induced expectations of pain relief (24).

Crucially, pre-stimulus alpha activity (directly before the onset of pain) (25–29) is

related to pain experience; higher alpha is associated with lower pain ratings and vice

versa (28,29). A number of studies have also identified differences in resting-state

alpha activity comparing patients with chronic pain to pain-free controls (30–34).

Importantly, a similar inverse relationship between alpha and chronic pain intensity

has been found (35). Thus, stimulating the brain to increase alpha could lead to a

reduction of chronic pain.

Rhythmic visual, auditory, or transcranial alternating current stimulation (tACS) can be

used to increase alpha activity non-invasively. When stimulation is applied at the alpha

frequency (i.e., 8-12Hz) this results in an enhancement of alpha via a mechanism of

entrainment, whereby neural oscillations synchronize to the frequency of the stimulus.

As more neurons synchronize, this is registered as an increase in alpha activity (36).

Studies have demonstrated a reduction in experimental pain with alpha frequency

tACS (37), and with auditory and visual stimulation (38,39). More recently, a 2019

study has demonstrated first evidence that increasing alpha with tACS is also effective

in relieving chronic pain (40).

6

Whilst these studies have shown positive results in an experimental setting, there is a

clear need to translate this into a practical technology that can be used by patients for

pain relief at home. For this purpose, we developed a technology for presenting alpha

range visual and auditory stimulation integrated within a smartphone application (app).

Although purpose-built goggles are used in a lab setting, the app can be used with a

virtual reality (VR) headset for a similar experience. Headphones are used to deliver

the auditory stimulation in the form of binaural beats, whereby the right and left ears

receive tones at slightly different frequencies (e.g. 440Hz and 450Hz) such that the

perceived beat frequency is the difference between the two frequencies (e.g. 10Hz)

(41).

The design and development of this app must be guided by potential future users of

the technology to ensure it meets their needs, as per the recent NICE Evidence

Standards Framework for Digital Health Technologies (March 2019) (42). Although the

importance of assessing ‘acceptability’ is well-established, the term has previously

been criticised as illǦdefined, underǦtheorized, and poorly assessed (43). In this work,

we therefore drew on a recently proposed Theoretical Framework of Acceptability

(TFA) (43) to structure our investigation. The concept of ‘usability’ is also captured

within the framework to explore how easy to use, intuitive and accessible the app was

for users.

The aim of this study was therefore to gain qualitative feedback from patients with

chronic pain regarding the acceptability and usability of a brainwave entrainment

smartphone app, to guide further design and development.

7

MATERIALS AND METHODS

This study used qualitative methodology to explore and gain in-depth understanding

of participants’ experiences and views (44).

Participants

Inclusion criteria:

adults aged 18 or older

clinically significant pain (for which they have sought medical input) for

more than three months

able to consent to participation.

Exclusion criteria:

personal or first-degree relative history of epilepsy or convulsions/seizures

history of discomfort or eye twitching with flashing lights

severe or frequent headaches

current or planned hospitalisation during the study.

Sixteen participants were identified from local musculoskeletal, rheumatology and

rehabilitation clinics. The first 14 participants also took part in a lab-based visual or

tactile entrainment study with author LJA, which measured levels of entrainment with

EEG whilst assessing subjective pain scores. Although these studies used similar

brainwave entrainment (BWE) technology, the participants’ first experience of using

the BWE smartphone app was for this qualitative study. The subsequent two

participants were recruited directly into this study by author HNL. Participants were

given a verbal explanation and a participant information sheet explaining the study.

8

Written informed consent was obtained after 24 hours. One participant dropped out

immediately after consenting.

Participants had a mean age of 47 years (range 22-71) (table 1). Of the 15 participants

completing the study, 14 (93%) owned a smartphone, whilst 13 (87%) stated that they

used apps on a regular basis. Only one participant (7%) felt that they were not

confident in downloading and using apps. Thirteen (87%) owned a laptop or PC

computer, whilst six (40%) owned a tablet computer.

Table 1. Participant demographics and pain condition.

Participant No. Age Gender Pain Condition

1 23 F Chronic widespread pain (CWP)

2 51 M CWP

3 62 F CWP

4 50 F Osteoarthritis

5 71 M Cervical stenosis, osteoarthritis

6 39 F CWP

7 47 F Osteoarthritis

8 47 F CWP

9 47 M Musculoskeletal groin pain

10 22 F CWP

11 35 F CWP

12 1 - - -

13 32 F CWP

14 66 M Cervical stenosis

9

15 48 M Osteoarthritis and haemophilia

16 69 F Radiculopathy

1 Participant dropped out prior to data collection.

The smartphone application

The BWE smartphone app was developed by authors NKJ and AC as a research

tool. On the home screen are options for “visual stimulation” and “binaural beats”. Each

option has a choice of four or five different frequencies, the lowest being 1Hz and the

highest either 23Hz (for binaural beats) or 18Hz (for visual stimulation) (Figure 1). Not

all the frequencies are within the alpha range and it was therefore not expected that

these would achieve alpha brainwave entrainment; the recommended frequency

setting for pain relief is 10 Hz based on preliminary evidence in healthy volunteers.

However, having multiple frequency options within the app will allow the flexibility of

testing different frequencies for pain relief in future efficacy trials.

The participants also had the option of choosing between visual and auditory

stimulation as it was felt that allowing individuals to have a choice would make the

study more inclusive, as some individuals with chronic pain can be intolerant to specific

sensory modalities. This is an important aspect of user involvement in the iterative

design and development process of the technology. The binaural beats option is

designed for use with standard headphones/earphones. The visual stimulation option

should be used with the phone placed inside a standard VR headset, such that it can

be viewed directly in front of the eyes. Volume and brightness can be adjusted as per

the participant’s preference using the phone settings.

10

(a) (b) (c)

Figure 1. (a) Virtual reality headset; (b) smartphone showing frequency options for

binaural beats (auditory) stimulation; (c) smartphone showing frequency options for

visual stimulation.

Study Methods

At an individual face-to-face meeting with author HNL, participants were provided with

an Android phone, a VR headset and earphones to use for the duration of the study.

Participants received a demonstration of the app and were given the opportunity to

practice using it. Participants were encouraged to use the app at home at least once

a day for 10 minutes in order to gain meaningful feedback. As there is no available

data on BWE use longer than 40 minutes, it was suggested that they do not exceed

this limit. Participants were provided with a contact email address and telephone

number for the research team in case of any questions or issues with the app during

the study period.

11

Data Collection

After four weeks, the participants were contacted by telephone for a semi-structured

interview with author HNL lasting an average of 28 minutes (range 16–55). An

interview guide was developed by authors HNL and JB, based on the topics of:

technology literacy; the participant’s pain condition; experiences of using the app

(usability, impact on activity, likes and dislikes); and smartphone technology in

healthcare. Questions were structured around the interview guide, but the semi-

structured approach allowed for exploration of relevant topical trajectories in the

conversation. Interviews were recorded on a secure laptop using Audacity software

(45). Recordings were then transcribed verbatim and any identifiable data removed.

Data Analysis

Interview findings were analysed thematically using Template Analysis (46), a style of

thematic analysis that provides a systematic approach to categorising qualitative data

in hierarchical clusters. Template Analysis permits the definition of ‘a priori’ themes –

these are themes identified as likely helpful and relevant to the research focus, which

are then refined and developed through analysis. Our coding template was structured

around the TFA (43), a multi-faceted construct consisting of seven domains (in the

context of this work, the term “intervention” refers to use of the app in the home

environment):

Affective Attitude (how an individual feels about an intervention)

Burden (the perceived amount of effort it takes to engage with an

intervention)

12

Ethicality (the extent to which an intervention is congruent with an

individual’s belief system)

Intervention Coherence (how an individual understands the aims of an

intervention and how it works)

Opportunity Costs (the extent to which an individual needs to compromise

existing benefits or values to engage with the system)

Perceived Effectiveness (how well an intervention achieves the desired

outcomes)

Self-efficacy (an individual’s level of confidence that they can engage in the

behaviours required to participate with an intervention)

Analysis followed the procedural steps described by King and Brooks (47) from what

they describe as a qualitative neo-positivist position (for the purposes of this study, we

have taken a realist approach that assumes an unproblematic relationship between

our participants’ accounts and [a shared] external reality). Preliminary coding involved

highlighting data of relevance from interview transcripts and assigning these segments

to our a priori headings. Segments were then grouped into sub-themes to capture the

finer detail of participant accounts. Once a complete analysis template was

constructed, this template was applied to the full data set. Throughout analysis, the

validity and consistency of coding was discussed between authors HNL, MS and JB

and the final thematic framework agreed by the full research team.

13

Ethical Considerations

Ethical approval for this study was gained from the Health Research Authority (IRAS

Project ID 223210). This study was nested in an application for the wider Neuro-

therapeutic Interventions for Pain (NTIP) Project by the Human Pain Research Group

at the University of Manchester, which also included EEG and neurofeedback studies

on the alpha brainwave response in chronic pain. Participants could withdraw from the

study at any point up to data analysis without giving a reason.

RESULTS

The TFA defines acceptability as ‘a multi-faceted construct that reflects the extent to

which people receiving a healthcare intervention consider it to be appropriate, based

on anticipated or experienced cognitive and emotional responses to the intervention’

(page 4, Sekhon et al) (43). Table 2 shows our analysis template including all top-level

themes (derived from the TFA) with sub-themes. Below we describe how participants’

accounts of using the BWE smartphone app mapped onto the TFA domains with

illustrative quotes.

14

Table 2. Themes adapted from the Theoretical Framework with subthemes

from data analysis.

Themes Subthemes

Approach to trying out the app: Affective attitude and ethicality

The impact of living with pain

Current management options

Perceived effectiveness Extent of pain relief

Additional reported effects

Opportunity costs and burden

Fitting app use into everyday life

Negative effects of app use

Intervention coherence and self-efficacy

Understandings of and familiarity with technology

Intervention usability and suggestions

for development

Approach to trying out the app: Affective attitude and ethicality

In the TFA, ‘affective attitude’ refers to how an individual feels about an intervention

and ‘ethicality’ relates to how it fits into the individual’s personal values system,

influenced by personal experience. In our analysis, these domains were merged into

one theme describing individuals’ feelings about their pain condition and current

treatment options, which influenced their attitudes towards and willingness to try this

novel approach.

The impact of living with pain

Across participant accounts, participants described physical restrictions placed on

them by their pain condition. Participants also recounted isolation and social limitations

– their world becoming “smaller” in both a physical and social sense. Concurrent with

15

this was a sense of increased (but reluctant) dependency on close others. Anxiety,

stress and low mood were key features of the condition for many. Participants

frequently described their pain condition in expressive terms such as fighting a daily

“battle” and there was a feeling of desperation to be free from pain and able to live a

“normal” life.

Illustrative Quotes

P3 …when you’re in that sort of vicious circle, you don’t realise just how small

your life is getting. You stop doing things because it’s too much of a struggle,

and you start adjusting everything you do to manage the pain

P13 …it doesn’t matter what you do, you’ll never find a cure, there’s no cure,

there’s no pain meds, there’s no meds in the world that are going to make

you better

Current management options

Participants reported that the main treatments offered to them were pharmacological

therapies and that there was a lack of alternative options available. There was a

common feeling of being stuck between a rock and a hard place with regards to

efficacy and side effects of medication. Alternative treatment options were actively

sought and almost all had already tried other treatment strategies, often despite

significant personal expense. Five participants specifically voiced a willingness to try

anything that may potentially help relieve their pain.

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Illustrative Quotes

P7 …the constant ‘do I take pain killers and not be in pain, but then not be able

to function again?’. You know…It’s not always an easy decision

P1 Right now they don’t have many options for you. They just say we can put

you on medication and that’s it really. And that’s quite upsetting

Perceived effectiveness

Whether an intervention is understood as effective contributes significantly to

acceptability. In this case, participants were aware that they had been recruited on the

basis of their pain condition, but were not informed of any potential effects that they

may experience from using the app. However, it is worth noting that the last two

participants were recruited after a press release, which included information about this

technology that may have influenced their expectations. Notably, the perceived

effectiveness of the app was not exclusively related to pain relief. Indeed, there were

a range of ways in which participants interpreted the effectiveness of the app.

Extent of pain relief

This was a qualitative study focusing on usability and acceptability of the app design

and therefore clinical efficacy cannot be ascertained based on this feedback. However,

five participants did report a meaningful improvement in their pain symptoms after

using the app. Others had more mixed views or were uncertain about the impact on

their pain.

17

Illustrative Quotes

P15 It was miraculous. I reckon I’ve gone from, probably from reliant on anti-

inflammatories to 80% less…Yeah, I’m really keen to know about the science

a bit more and how it works, but at the moment I’m just happy feeling

confident that it works

P9 I haven’t noticed any difference…some weeks are better than others but

again I have no idea what that would be attributed to. I genuinely have good

weeks and bad weeks

Additional reported effects

The most commonly stated effect was relaxation, stated by 10 out of the 15

participants, which was felt to be very positive even if the individual’s pain level

remained the same. This was either the result of a direct ‘meditative’ effect from the

rhythmic stimulation or resulted from taking the time out to quietly sit and relax. In

addition to this sense of relaxation and restfulness, three participants reported falling

asleep when using the app. However, it was less apparent whether there was any

effect on overnight sleeping.

Illustrative Quotes

P4 You could just go off into your own little world with it…It was comfortable, you

could just relax into it and let time pass by quite happily

P11 I think the massive benefit for me as I said was almost like a calming

meditative. That particular 7Hz programme on the audio became almost like

18

a calming, zoning out, meditative thing for me to use…for me that was a really

fantastic positive effect

P5 I did them both [visual and auditory stimulation] lying on a sofa, with my head

on a pillow on one arm and spread out across the sofa. So that was fine. In

fact, once or twice I fell asleep it was that peaceful

Opportunity costs and burden

The TFA defines ‘opportunity costs’ as the “extent to which benefits, profits or values

must be given up to engage in the intervention”. ‘Burden’ is the perceived amount of

effort it is likely to take to engage with an intervention. The two have been merged into

one theme in our analysis, describing how the intervention fitted into participants’ daily

lives and the impact on their activities, responsibilities or relationships.

Fitting app use into everyday life

Some participants found that they had no difficulty fitting the app into everyday life.

However, others found it challenging to take time out from their existing responsibilities

and felt uncomfortable doing so. Two participants felt that on occasion the

psychological effort required to use the app was too great, due to the low mood and

apathy associated with their condition. Three found it difficult to remember to use the

app and felt this placed additional burden on them. Several participants suggested

that the app could be modified to include a mechanism of receiving a reminder or

prompt. Others expressed the view that if effective, then incorporating the app into

your life is easy, as one would always make time to use something that is beneficial.

19

Illustrative Quotes

P4 It’s fine during the day when I’m at home on my own. But when you’re feeling

a little bit of pain in the evening…to either go out of the room or stay in the

living room with the rest of the family and saying ‘I’m just putting this on’,

putting that on then didn’t seem to fit right with me

P15 Because I think my view is that, if you’ve got something that you’ve got a

positive association with, using it isn’t negative and isn’t a hindrance

P2 Yeah. Umm there was some days I didn’t use it…there were certain days

when I had a very low mood and you know it was like, you know, I couldn’t

be bothered with anything

P1 But it crept down to once a week because it just became quite difficult to

remember to do it. At first it’s a novelty, you do it a few times a week, then

it’s hard to remember, so maybe a sort of reminder within the app would be

good…

Negative effects of app use

Some participants reported negative effects when using the app. Five participants

reported exacerbation of existing headaches or a new headache. Several described

an increased sensory sensitivity associated with their condition, which affected their

20

tolerance of the app. Overall, participants were positive about the VR headsets,

however two mentioned that the headset was heavy and lighter headsets would be

preferable. Finally, participants also found that the all-encompassing nature of the

stimulation, particularly with the visual stimulation via the headset, could be

overwhelming and provoke anxiety.

Illustrative Quotes

P7 With the sounds I just used it for about 10 minutes because after that it tended

to give me a bit of a headache. But that may have been again something to

do with the volume

P6 I think for someone like me, maybe for someone who has other types of pain

it might be helpful, but I think because mine is nerve related and already on

those pathways, I’m feeling a lot of discomfort. You know, it just felt like it

was exacerbating the pain

P10 It just made me feel a little bit anxious… It was mainly just the, how bright it

was. I don’t really do well with flashing and things…It just makes me feel quite

dizzy and anxious

Intervention coherence and self efficacy

This theme merges the TFA domains ‘intervention coherence’ and ‘self-efficacy’ and

describes how participants understood the intervention, perceived barriers and

enablers to using the app, what aspects of the app were most important to users and

what might be modified to meet their needs.

Understandings of and familiarity with technology

21

Participants were interested in the concept of using technology as a condition

management strategy and wanted to know more about the science behind the app.

Participants talked in positive terms about ways in which the app could be individually

tailored and provided a heightened sense of personal control of condition

management.

Most participants were very comfortable around technology and used multiple types

of technology daily, including smartphones, laptops and tablets. They also used apps

on a regular basis, with some having previously used apps for health or wellbeing.

There was a recognition that smartphones are now very commonplace and an

essential part of everyday life for many. However, participants recognized that this

would not be the case for everybody, in particular those from the “older generation”.

Illustrative Quotes

P7 I think obviously I’m a very confident user of technology. But I think not

everybody is. My mother-in-law for example, will only use the computer if

somebody puts it in front of her. She wouldn’t dream of having a mobile

phone

P15 It’s making me think about the science of what’s going on. And the brain side

of things…It’s quite profound really

P10 It could have a really big impact on the way you feel about something if you

feel like you’re actually helping yourself and you’re not relying on someone

else to fix the problem

Intervention usability and suggestions for development

22

Feedback from early patient and public involvement workshops indicated that the app

should be kept simple and straightforward. Participants in the study generally agreed

with this sentiment and appreciated the app’s simplicity of design and ease of

navigation. Participants were also asked about the VR headsets to gain an idea of

whether using a VR headset would be a limitation for any users. Although most found

it quite simple, some felt that it was ‘fiddly’ to use.

Visual and auditory stimulation had similar levels of acceptability amongst participants:

six participants preferred the visual stimulation, five preferred the auditory stimulation,

no preference was expressed by two participants, and two tried only the visual

stimulation. Reasons given for preferring the visual stimulation were that it was more

immersive and it was easier to “zone out” when using it. Reasons for preferring the

auditory stimulation included finding the VR headset uncomfortable and finding the

binaural beats more relaxing.

However, there was a range of preferences with regards to the frequency used.

Interestingly, some individuals preferred the slower frequencies, finding them more

calming or less intense. Contrastingly, others preferred the higher frequencies,

commenting that they perceived more of a stimulatory effect from the faster speeds,

and thus felt it was more likely to relieve their pain.

Illustrative Quotes

P5 Yeah it was so easy to use, you know, you just had to tap the screen…it was

just brilliant, brilliant

23

P11 Always a slower speed would be a preference, because for me

psychologically I just found it calmer and the same with the sounds as well

P8 I preferred the higher ones if I’m honest…I just seemed to get better effects

from them

DISCUSSION

This study demonstrates preliminary support for the acceptability and usability of the

BWE app for users with chronic pain.

There is increasing awareness of the need to address acceptability in the development

of new healthcare interventions. Users gain greater clinical benefit from treatments

they consider to be acceptable, as they are more likely to use the treatment as advised

(43). Surprisingly, the perceived effectiveness of the app was not related to pain relief

alone, but benefits such as relaxation and “zoning out” were considered as equally

positive results.

The app provides a self-directed tool for BWE in the home environment. Previous

studies have demonstrated that using a healthcare app can empower patients by

providing a means to self-manage their condition (48). It is increasingly recognised

that complex health conditions such as chronic pain require personalised treatments,

and effective “e-health” technologies, such as smartphone apps, can facilitate this

(49). This is supported by the European Commission’s e-Health Action Plan (50).

24

The home-based nature of the app is likely to be more acceptable to patients who

struggle to engage in activities outside of the home environment. Given the largely

negative attitudes towards pharmacological treatments amongst participants, there

were clearly articulated wishes for alternative approaches to pain management.

Participants were keen to emphasise their willingness to try a novel approach and their

openness to using the app (although expectations about cure/control of symptoms

may need careful management). Smartphone-based technologies are increasingly

used as healthcare tools, as they are accessible and affordable. Although there is

some discrepancy in smartphone use between age groups and social classes, the

trend of number of users has been steadily increasing amongst all user groups (51).

It is therefore an effective means of targeting groups who may traditionally struggle to

access healthcare.

The term “usability” is used in a broad sense in the context of the TFA to encompass

the users’ perspectives on how easy to use, intuitive and accessible they found the

app. However, there have been many proposed definitions of usability in the context

of software development (52,53), including in the international standard ISO 9241-

11:2018, which focuses on effectiveness (the ability of users to achieve the intended

goal), efficiency (resources consumed in achieving the intended goal) and satisfaction

(referring to how users feel) (52,54). Whilst this study did not use metrics to measure

the above factors, nonetheless an interpretation can be made based on qualitative

user feedback. A fundamental aspect of the study design was recruiting participants

with chronic pain, who are the intended end users of the intervention, and setting the

study in the home environment. This was crucial in assessing the usability of the app

in the intended context of its clinical application (53).

25

Participants generally found the app to be easy to use. All participants were able to

use both the auditory and visual stimulation at the different frequency settings and

responded positively to its simple design. A ‘user-friendly interface’ is an essential

feature of an effective health app according to Higgins in his 2016 commentary on

smartphone apps for health and fitness (55). Perhaps in contrast to this were the

suggestions from participants to incorporate other features, such as reminders or pain

monitoring, which may complicate the design. However, such features have been used

effectively in other health and wellness apps (56,57).

Additionally, participants were able to use the VR headset with little difficulty. However,

several participants commented on the fiddly nature of placing the phone within the

headset. A key usability goal was to ensure that the intervention is accessible to all

potential future users and this may be an issue for users with dexterity difficulties. One

of the recognised limitations of health and wellness apps is that they may not always

be suitable for users with different needs or disabilities (55). A possible solution to this

is a bespoke set of goggles, which may also be lighter and more comfortable for users.

Another recognised limitation is the need for active engagement from the user (55).

This was echoed by the participants, who found that at times they lacked the energy

or will to use the app. This is likely to be a common difficulty for those with chronic pain

or mood disorders and should be taken into consideration.

As well as the positive effects mentioned above, some participants experienced mild

headaches or discomfort from using the app. In some cases, this was felt to be linked

to their pain condition. No similar effects have previously been reported (38,39).

26

However, this is the first study of its kind using BWE in the home setting on a regular

basis. These adverse effects should be taken into consideration when applying the

intervention in the clinical setting.

As a qualitative study, findings cannot be used as a means of assessing clinical

efficacy. However, the semi-structured interview process allowed for full exploration of

what was deemed to be important to each participant, providing rich and useful data.

One limitation was that the interviews were all carried out by a single researcher with

a clinical background. It is possible that different ideas may have arisen if the

interviewer had been from an app development background for example. However,

the study was performed in collaboration with professionals from a range of disciplines

including engineering, psychology and pain medicine, who contributed at each stage.

Analysis was carried out by one researcher, but regularly reviewed and discussed with

other members of the research team and the final thematic framework agreed by the

full research team.

Moving forward, this study will guide the further development of the BWE app.

Alongside this, further efficacy studies will be warranted, using quantitative measures

of pain response to the app in the home setting. Dose response and duration of effect

should also be established, as well as understanding the variability of response

between individuals. Understanding the phenotype of responders versus non-

responders may enable clinicians to target appropriate individuals for whom it is likely

to be effective in future.

27

Although specifically used in the context of chronic pain in this study, BWE has the

potential for a range of clinical applications in fields such as sleep and mood disorders.

These findings are therefore applicable to other health contexts. Despite the

increasing prevalence of healthcare apps, they are rarely developed collaboratively

with input from app developers, healthcare professionals and patients (58). This study

therefore adds to our understanding of what is important to end users of such

technologies and may provide useful insight for the development of other healthcare

apps for this patient group.

CONCLUSIONS

BWE technology has been a recent focus of interest in the context of managing chronic

pain. This technology can be delivered easily and affordably through a smartphone

app. This study presents preliminary evidence for the acceptability and usability of the

app in the home setting. Whilst studies are ongoing into the clinical efficacy and dosing

response of BWE in pain, this study provides the user perspective to ensure that the

design and functionality of the app meet the needs and wishes of users with chronic

pain.

28

Conflicts of Interest: The authors declare that there is no conflict of interest.

29

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